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[The startle reaction of the newborn infant]
1Klinik und Poliklinik für Kinderheilkunde, Bereichs Medizin der Martin-Luther-Universität Halle-Wittenberg.
Insights
Neonatal startles, characterized by muscle contractions, significantly impact cardio-respirograms. Startle frequency decreases with age, with no correlation to serum chemistry in infants.
Area of Science:
- Neonatal physiology
- Developmental neuroscience
- Sleep studies
Context:
- Startles are motoric symptoms influencing neonatal cardio-respirograms.
- Previous research has not fully elucidated the developmental trajectory of startles in relation to sleep states and postnatal age.
Purpose:
- To investigate the dependence of neonatal startles on behavior, gestational age, postnatal age, and serum chemistry.
- To quantify startle frequency during different sleep stages (NREM and REM) in premature and full-term neonates.
Summary:
- A polygraphic study of 12 premature and 24 full-term neonates revealed significantly higher startle frequencies per hour during non-rapid eye movement (NREM) sleep compared to rapid eye movement (REM) sleep on the second day after birth.
- Specifically, full-term neonates exhibited 10.6 startles/h in NREM sleep versus 1.9 in REM sleep, while premature infants showed 3.6 startles/h in NREM sleep versus 0.6 in REM sleep.
- By 4 weeks of age, startle frequency diminished significantly, with full-term neonates showing none and premature infants only 0.2 startles/h in NREM sleep. No correlation was found between startle frequency and serum levels of glucose, calcium, or magnesium.
Impact:
- This study provides normative data on the developmental decline of startle responses in neonates.
- Findings contribute to understanding normal neurological development and sleep physiology in early infancy.
- Highlights the transient nature of startle reflexes and their diminishing role as infants mature.
Abstract:
Startle characterized by a spontaneous or reflecting motoric symptom like brisk, shortlasting and generalized contraction of limb and trunk muscles influence considerably the cardio-respirogram of neonates. The dependence of startles on behaviour, gestational age and postnatal age as well as on levels of blood glucose, calcium and magnesium in serum has been studied in 12 premature infants and in 24 full term neonates by means of polygraphic conditions. The average of 3.6 +/- 3.0 complete startles in premature infants and of 10.6 +/- 8.7 startles in full term neonates per hour non rapid eye movement-sleep, observed on second day after birth, was significantly higher than the frequency of startles in rapid eye movement-sleep measured as 0.6 +/- 0.9 and 1.9 +/- 2.1 complete startles respectively. In an age of 4 weeks there were no complete startles demonstrable in full term neonates and only 0.2 complete startles/h in non rapid eye movement sleep could be observed in premature infants. There was no correlation between frequency of startles and investigated chemical parameters in serum.